This application addresses broad Challenge Area (02) Bioethics and specific Challenge Topic, 02-DK-105: Allocation of Scarce Transplanted Organs. The Department of Health and Human Services'"Final Rule" for organ allocation charges the Organ Procurement and Transplant Network (OPTN) with implementing and maintaining policies for equitable organ allocation, defined as the distribution of "organs over as broad a geographic area as feasible". Currently there are 11 geographic regions that define boundaries directing organ distribution. While the regional system is intended to facilitate allocation, reduce cold ischemia time and encourage donation, data demonstrate that the current regional boundaries disadvantage some patients in greatest need of transplants and pose economic inefficiencies for the healthcare system. Patients with similar disease severity across the nation experience substantially different mortality rates as a consequence of regional organ availability. The purpose of the proposed project is to design and simulate organ allocation systems using novel geographic patterns of sharing, and to estimate expected clinical, socio-demographic and economic implications. A collaborative, multi- institutional research program integrating expertise from the Saint Louis University Center for Outcomes Research, Johns Hopkins University, the Dartmouth Institute for Health Policy and Clinical Practice, and the University of Washington Surgical Outcomes Research Center will be applied to accomplish three major Aims: 1) To design and evaluate optimal geographic regions of liver and kidney allocation that address organ-specific distribution goals. Currently the stated goal of liver allocation is to minimize waitlist mortality by transplanting patients at the highest Model for End-Stage Liver Disease (MELD) disease severity scores, and the stated goal of kidney allocation is to minimize waiting time. A mathematical optimization approach using integer programming will maximize benefits to waiting candidates across the county by drawing regions that equalize MELD at transplant among liver candidates and equalize waiting time for kidney candidates. 2) To quantify the impact of a novel geographic sharing system on disparities in liver and kidney transplant access across individual socio-demographic characteristics. Through a comprehensive examination of patient-level factors and granular measures of healthcare system geography (e.g., hospital referral regions), the implications of the current regional system compared to optimized geographic sharing will be assessed for transplant access and outcomes across individual socio-demographic traits and local units of care delivery. 3) To estimate the economic impact of a novel sharing system on costs of care for end-stage liver and kidney diseases. Linkages of clinical data in the OPTN registry will be performed with financial data from Medicare, private insurers, and leading providers of care during the transplant hospitalization to construct a unique database for health economics research. Using a regression framework, the economic implications of a new sharing system for the costs incurred in the care of patients with end-stage liver and renal diseases before, during and after transplant will be estimated. Project Summary/Narrative Organ donation is a precious, life-saving resource for patients with end-stage organ failure that must be allocated as equitably as possible. At present, the United States is divided into 11 geographic regions that direct organ distribution in efforts to place organs quickly and encourage local donation, but recent data demonstrate that the current regional system disadvantages some patients in greatest need of transplants and poses economic inefficiencies. The purpose of the proposed project is to design organ allocation systems using novel geographic patterns of sharing that better balance donor and recipient populations, and to estimate the expected impact of novel organ sharing on waiting times, organ and patient survival, and costs to the healthcare system.